Angular adjustment mechanism, surgical alignment guide and surgical instrument assembly

Abstract

An angular adjustment mechanism for a surgical instrument is described. The mechanism comprises an adjustment member ( 102 ) configured for rotation about a longitudinal axis ( 122 ), the adjustment member comprising a plurality of pairs of facets ( 134 ) arranged about the longitudinal axis. Each of the plurality of pairs of facets defines a respective angled axis ( 148 B, 148 C) at an angle ( 150 B, 150 C) relative to the longitudinal axis. A pivoting member ( 104 ) is arranged to pivot about a pivot axis perpendicular to the longitudinal axis and comprises a recess ( 128 ) for receiving the adjustment member and engaging one pair of the plurality of pairs of facets. This provides an angular adjustment mechanism in which facets on the outside of the adjustment member engage corresponding surfaces in a recess on a pivoting member. The use of facets provides a secure connection while allowing a greater degree of angular adjustment and providing a further benefit of simple operation.

The invention claimed is: 
     
       1. A surgical instrument assembly comprising:
 an adjustment member comprising a plurality of pairs of facets arranged about a longitudinal axis, each pair of facets meeting along an edge, the adjustment member being rotatable about the longitudinal axis; wherein each edge of the plurality of pairs of facets lies along a line intersecting the longitudinal axis at an angle, each edge defining a different angle with respect to the longitudinal axis; 
 a pivoting member pivotable about a pivot axis that is perpendicular to the longitudinal axis, the pivoting member having a recess sized to engage at least one pair of the plurality of pairs of facets; and 
 a cutting guide attached to the pivot member. 
 
     
     
       2. The surgical instrument assembly of  claim 1 , further comprising a intramedullary rod defining an intramedullary axis, and wherein the angular adjustment mechanism is connected to the intramedullary rod, and the longitudinal axis of the adjustment member is coaxial with the intramedullary axis.